(a) Prohibited Uses. In a civil or criminal case, evidence of the following is not admissible against the defendant who made the plea or participated in the plea discussions:....

(4) a statement made during plea discussions with an attorney for the prosecuting authority if the discussions did not result in a guilty plea or they resulted in a later-withdrawn guilty plea.

A question that has split the courts is how strictly the phrase "plea discussions with an attorney for the prosecuting authority" should be construed. For instance, does Rule 410(a)(4) require the physical presence of the prosecutor to apply? That was the question addressed by the Ninth Circuit in its recent opinion in United States v. Zamastil, 2013 WL 6698624 (9th Cir. 2013).

In Zamastil, William Zamastil was convicted of first-degree murder. After he was convicted, he appealed, claiming, inter alia, that the district court erred in allowing for the admission of evidence in violation of Rule 410(a)(4).

Specifically, Zamastil initially met with an FBI agent and told him that he wanted to negotiate a plea deal. That agent told him that he had no authority to negotiate a plea also told him that he would check with the prosecutors. Then,

In response to Zamastil's request to work out a deal, Assistant U.S. Attorney Bates Butler sent the following letter to Zamastil:

I have been informed by the Federal Bureau of Investigation that you possess information pertaining to homicides which may have occurred in Southern Arizona. While I am willing to consider some negotiated agreement in which I would seek a concurrent sentence for you if the information you provided incriminated you in other homicides, you have not yet provided sufficient information upon which I can base a decision. I have spoken with W. Randolph Stevens, Jr., Chief Criminal Deputy Pima County Attorney, and he agrees with me.

Mr. Stevens and I are unwilling to “buy a pig in a poke.” Before we make any commitments for our respective jurisdictions we will need some proffer from you about the incident about which you possess information. We need to know whether or not you were the individual in any situation who actually committed the act which directly resulted in an individual's death. In other words, what was the extent of your involvement in these homicides?

Upon receipt of preliminary information from you, I will consult with Mr. Stevens about whether any deal can be made with you for a concurrent sentence.

Thereafter, the FBI agent met with Zamastil again, during which time Zamastil made the incriminatory statements that were admitted at trial. For the majority, this rendered Rule 410(a)(4) inapplicable because Zamastil's statements were not "made during plea discussions with an attorney for the prosecuting authority...."

But, according to the dissent,

Once the prosecutors became involved, directly communicated with Zamastil, invited him to make a proffer in aid of reaching a deal, and allowed him to make a limited waiver to provide prosecutors with information they would need to reach an agreement, there is only one way to interpret these undisputed events: negotiations had begun. True, no deal had yet been reached nor had an offer been tendered—they were only in the initial “Whaddya got?” stage of the negotiation dance. There is no question, however, that the dance was under way. As a result, all of Zamastil's statements made to Doss and Butler after Butler's October 2, 1980 letter— i.e., the “limited purpose” statements he made to Doss on October 29, 1980 and the letters he sent to Doss and Butler on May 20, 1981—should have been deemed inadmissible under Rule 410.

As support, the dissent noted that "other courts have held [that] it would be overly formalistic to read Rule 410 as only ever applying when the attorney is actually physically present for the negotiations."